In a current large building construction such as a manufactory construction, it is essential to adopt a through-passage forming apparatus or molding apparatus on preservation of a space required for each one of the through-passages. After poured into a circumambiency of the through-passage forming apparatus or molding apparatus, the concretes are set to form the through passages treated as ducts, supplying-water pipes or cable passageways, besides each of the concrete floor, simultaneously. In especial, a concrete floor located between a working level and a bottom returning-air passageway level of a high-class clean room needs disposal of the through passages thereon for ventilation. This would result in maintaining a higher ventilating quantity, elongating a length of the through passage and enlarging the through passage diameter, simultaneously, in addition that a thickness of the concrete floor is thickened to raise a bearing capacity of the manufactory floor. However, the elongation of the through-passage length would make a stressed region of the through-passage forming apparatus or molding apparatus against the concretes being widened.
Several conventional technologies, for examples, a Japanese Utility Model Publication No. H5-32586, a Japanese Pat. Publication No. H11-81663 and a Japanese Pat. Publication No. 2000-145142, have provided various through-passage forming apparatus or molding apparatus, most of which structurally and primarily have an upper cover, a lower cover, a hollow standing sleeve and a single retaining assembly. FIG. 1 illustrates an exemplar upon the Japanese Pat. Publication No. 2000-145142, which is explained as following: a hollow standing sleeve 5 has an upper opening and a lower opening both communicated with a hollow space thereof, wherein the lower cover 2 and the upper cover 4 both are formed with an aperture or an inner-threaded hole on a central position thereof. In assembly, said single retaining assembly 3 could be accommodated within the hollow space of the standing sleeve 5. The upper cover 4 is used to cover the upper opening of the standing sleeve 5 and the lower cover 2 is used to cover the lower opening of the standing sleeve 5. Then, by threads and/or an additional nut located on ends of the retaining assembly 3, the two opposite ends of the retaining assembly 3 are respectively up-and-down screwed to the upper and lower cover 4, 2. This leads the lower cover 2, the upper cover 4 and the standing sleeve 5 triple to be integrated. The through-passage forming apparatus or molding apparatus is merely joined in a vertical direction to a horizontal construction molding of the concrete floor by its lower cover 2 or the end of the single retaining assembly 3. However, under a factual construction, the concrete would principally impact the through-passage forming apparatus or molding apparatus along a horizontal direction relative to the apparatus when poured. If the through-passage forming apparatus or molding apparatus is infirmly fastened on the horizontal construction molding of the concrete floor, the impact of the being-poured concrete very readily slants or deforms the through-passage forming apparatus or molding apparatus so that the through passage might be deformed or damaged after the concrete floor is set-to-formed. Additionally, only by respectively screwing the single retaining assembly to the central retaining points of said upper and lower covers 4, 2, the upper and lower covers 4, 2 might easily become slanted or deformed as long as undergoing the pressure and thereby slip in a direction along a sleeve wall of the standing sleeve 5. This eventually invokes the standing sleeve 5 deformed and slanted. Moreover, the upper cover, the lower cover and the retaining assembly would be stripped and removed from the above-mentioned current through-passage forming apparatus or molding apparatus after the formation of the concrete floor, only exception of the standing sleeve which is reserved within the through passage of the concrete floor. This would invoke an annular slit occurring between the sleeve wall of the standing sleeve and a circumference of the through passage wall of the concrete floor and exposed to the outside with a possible dusty precipitation or a straining damage possibly occurring from the through-passage wall undergoing an external force. It is possible happened that the concrete floor compresses the standing sleeve since stressed under the construction.
Accordingly, it is essential to develop a through-passage molding apparatus capable of reinforcing its entire structure to resolve the aforementioned problem.